Evaluation of Engineering Properties and Geological Hazards in the Ha’il Economic City Area
Turki E. Al Sehly, Ahmed M. Youssef, Abdullah A. Sabtan, and Waleed A. Al Aklouk
The Prince Abdul Aziz Bin Mosaid Economic City (Ha’il Economic City) in the Kingdom of Saudi Arabia is one of the pioneer projects and represents a corner stone for the new development activities for Ha’il region. The project was planned by the General Authority for Investment and is a key element of the initiative of Saudi Arabia recently to develop its economy, to generate regional growth and job creation for youth. The New Economic city is located to the north of the Ha’il city. The study area covers an area of ~156 km2. In general, Ha’il region is located in north-central part of Saudi Arabia. One of the main objectives of the establishment of the new economic city is to attract investors, entrepreneurs and developers from around the region to become a major focus in the field of logistics, information technology, and traditional building materials, infrastructure, and agricultural industries, education and smart infrastructure. Fundamental facilities of this project include all infrastructure of residential, commercial, industrial, and a new international airport as well as a dry port facilities in addition to other vital city services complementary to economic development.
The present study aims to evaluate the physical and engineering characteristics of surface and subsurface soil and rocks in the new economic city of Ha’il, by providing a new engineering geological map, and assessment of geological hazards that have a negative impact on the city. To accomplish this study several tools have been used including: (1) geological and topographical maps, (2) satellite images, (3) use of previous data and reports that have been obtained from the consulting offices and municipality of the region (4) conduct many field investigations and boreholes as well as desk and laboratory studies.
The present study showed that:
1. The study area contains many geologic units including surface sand accentuation that cover in some areas sandstone and granitic rocks.
2. The study showed that the soil at the upper section vary in its thickness from 0 to 12 meter. They include deposits that can be characterized into four units clayey sand, silty clayey sand, silty sand with gravel, clay sand with gravel, poorly-graded sand with clay, silty sand, silty clayey sand with gravel, and well-graded gravel with sand.
3. In other hand, rocks are exposed in some parts consists of sandstone and granite. These rocks include (1) sandstone which is characterized by as the slightly to moderately weathered, very low to moderate strength, RQD is very poor to fair, and the joint spacing range between 6 and 20 cm, (2) granite rocks which are characterized by moderate to highly weathering, very low to high strength, RQD is poor to good, and the joint spacing range between 20 and 60 cm.
4. Subsurface rock characteristics of the sandstone rocks are characterized by light brown, brown, dark brown, dark red, yellow and sometimes white; rock recovery ranges from 52 percent to 100 percent; RQD values range from very poor to excellent where the quality increases with depth; also ranges from completely weathered to fresh and/or slightly weathered where weathering decreases with depth. Strength value ranges from very low strength to low strength; the unit weight ranges from 1972.7 kg/cm3 to 2299.4 kg/cm3.
5. The engineering geological map of the new economic city has been prepared showing all different zones according to their physical and geotechnical properties. Different cross sections have been prepared also.
6. The most geological hazard that will have a negative impact on the area has been identified.
7. Various recommendations have been made that will help in development of different solutions to deal with the geological and geotechnical problems in the area.
Al Sehly, T.E., Youssef, A.M., Sabtan, A.A., and Al Aklouk, A.A., 2017, Evaluation of engineering properties and geological hazards in the Ha’il Economic City area: Saudi Geological Survey Technical Report SGS-TR-2012-11, 46 p., 35 figs., 27 tables.